Method of forming skid-proof leather-texture surface on metallic substrate

ABSTRACT

A method of forming a skid-proof leather-texture surface on a metallic substrate, including the following steps of: providing a metallic substrate; performing a first pretreatment to clean the surface of the metallic substrate; etching the surface of the metallic substrate through an etchant while using a etch-moderating agent to moderate the condition of etching. performing a second pretreatment, such as pickling or chemical polishing, on the surface of the metallic substrate; performing an anodic treatment on the surface of the metallic substrate to form an oxidized film having micro-porous structure thereon; activating the surface of the metallic substrate after the anodic treatment; dyeing the surface of the metallic substrate; sealing the micro-porous structure formed on the surface of the metallic substrate; and ash-removing to clean the metallic substrate.

BACKGROUND OF THE INSTANT DISCLOSURE

1. Field of the Instant Disclosure

The instant disclosure relates to a method of forming a skid-proofleather-texture surface on a metallic substrate; in particular, to ametal surface treatment technology to form a skid-proof leather-texturesurface on a metallic substrate

2. Description of Related Art

Generally, the metal surface treatment on a metallic surface refers tothe furnishing of a metallic surface after an initial fabricationprocess to change the surface feature of the surface through chemical ormechanical means. Where such method is also known as the process ofmetal surface furnishing

Nowadays, more and more electronic products have their metallic housingsor components furnished to be more aesthetically appealing whileincreasing their values. These processes include plating, anodizing,coating and etc.,

For those electronic products having a shorter life cycle, the influenceof the appearance of such products is yet more important. Theseelectronic products have to be apparently attractive enough in order tostimulate the consumer's impulse to purchase them within the shortesttime. However, the metallic housings of such products are oftenprocessed to be shiny and smooth and this may seem slippery for theconsumers in some aspect.

To address the above issues, the inventors strive via industrialexperience and academic research to present the instant disclosure,which can effectively improve the limitations described above.

SUMMARY OF THE INSTANT DISCLOSURE

The object of the instant disclosure is to provide a method of forming askid-proof leather-texture surface on a metallic surface. A delicateparticle structure is formed on the surface of the metallic substrate toovercome the problem of the surface being too slippery. Furthermore,such structure can also provide the users with a skid-proofleather-texture sensation.

In order to achieve the aforementioned objects, according to anembodiment of the instant disclosure, a method of forming a skid-proofleather-texture surface on a metallic substrate, comprising thefollowing steps of:

providing a metallic substrate;

performing a first pretreatment to clean the surface of the metallicsubstrate;

etching the surface of the metallic substrate through an etchant whileusing an etch-moderating solution to moderate the condition of etching;

performing a second pretreatment on the surface of the metallicsubstrate;

performing an anodic treatment on the surface of the metallic substrateto form an oxidized film having micro-porous structure thereon;

activating the surface of the metallic substrate after the anodictreatment;

dyeing the surface of the metallic substrate;

sealing the micro-porous structure formed on the surface of the metallicsubstrate with a sealing agent; and

cleaning the surface of the metallic substrate with a deducting agent.

According to an embodiment of the instant disclosure, the step ofperforming the first pretreatment on the metallic substrate includes asub-procedure of degreasing and water rinsing on the surface of themetallic substrate.

Based on the above, the instant disclosure has the following advantages:the texture of the surface formed through the etching process of theinstant disclosure is similar to a leather-texture surface having anirregular, uneven structure.

According to an embodiment of the instant disclosure, the process ofperforming the second pretreatment on the surface of the metallicsubstrate includes a pickling and a chemical polishing process toproduce a foggy surface on the metallic substrate. Furthermore, ananodic treatment is implemented on the uneven structure to form a moredelicate particle structure.

In order to further appreciate the characteristics and technicalcontents of the instant disclosure, references are hereunder made to thedetailed descriptions and appended drawings in connection with theinstant disclosure. However, the appended drawings are merely shown forexemplary purposes, rather than being used to restrict the scope of theinstant disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a flowchart of a method of forming a skid-proofleather-texture surface on a metallic substrate in accordance to theinstant disclosure;

FIG. 2 shows a perspective view of the metallic substrate in accordanceto the instant disclosure;

FIG. 2A shows a partially enlarged view of the portion A in FIG. 2;

FIG. 3 shows a perspective view of the surface of the metallic substrateafter the etching step of the forming method in the instant disclosure;and

FIG. 4 shows an enlarged perspective view of the surface of the metallicsubstrate formed from the method in the instant disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Please refer to FIG. 1 which shows a flowchart of a method of forming askid-proof leather-texture surface on a metallic substrate in accordanceto the instant disclosure. First of all, for the method of forming theskid-proof leather-texture surface disclosed in the instant disclosure,a metallic substrate is provided. Furthermore, the instant embodimenttakes the metallic housings of electronic devices for example, and inorder to be in accordance to the latter procedures, an aluminum alloysubstrate is adopted. Preferably, the instant embodiment utilizes thealuminum alloys of the 5000 and 6000 series coded in the AluminumAssociation, where the aluminum in the 5000 series are alloyed withmagnesium, and the aluminum in the 6000 series are alloyed withmagnesium and silicon.

The physical structure of the metallic substrate can be designedaccording to practical needs through mechanical processing. However, asandblasting process (abrasive blasting process) can also be performedon the metallic substrate prior to other processes in some cases. Sincesuch processes are easily known to any ordinary person skilled in therelated fields, no further illustrations will be provided herein. In thefollowing descriptions, the processing steps upon the metallic surface,the implementable parameters and the preferred parameters will beprovided herein.

Generally, there will be stains or oil remained on the aluminum alloysubstrate after the mechanical process. Therefore, the surface of thealuminum alloy substrate can be cleaned first before beginning thelatter procedures. For the instant embodiment, with reference to FIG. 1,the degreasing process P1 is implemented to remove the oil or stainsadhere to the substrate surface. This process can also be seemed as thefirst pretreatment.

For the parameters of the degreasing process, a degreasing agent havinga concentration of 1 to 50% can be utilized under a temperature thatranges from 10 to 90 degree Celsius, where the concentration of thedegreasing agent can also be adjusted according to practical needs.Since the instant embodiment utilizes the metallic housings ofelectronic devices for example, a preferred parameter for the degreasingprocess utilizes a degreasing agent having a concentration that rangesfrom 3 to 5% under a temperature which is approximately 50 degreeCelsius (note that all temperatures mentioned hereinafter refer todegree Celsius).

At least one time of water rinsing is required after the degreasingprocess to remove the remaining degreasing agent, where the number oftimes of water rinsing can range from 1 to 5 times, and the temperaturecan range from 5 to 95 degrees. Preferably, the water rinsing process isimplemented twice where the temperature is 25 degrees. In the latterprocedures, regarding the water rinsing processes required to remove thechemical substances remained from the prior procedure, the parameters ofthe water rinsing process is described in the above and shall notprovide any further illustrations.

Followed by the etching process S2 which etches the surface of themetallic substrate by using a chemical solution. Specifically speaking,the etchant is utilized to etch the surface of the metallic substrateand the etch-moderating agent (also known as the etch-control agent) isutilized to moderate the etching condition. For the instant disclosure,the metallic substrate is etched, particularly accompanied by theetch-moderating agent, before the anodic treatment is implemented toform a leather-texture, uneven structure on the surface of the metallicsubstrate, shown in FIGS. 2 and 2A. FIG. 2 shows a cross-sectionalperspective view of a metallic substrate 100, including a base layer 101and a surface layer 102. FIG. 2A shows a partially enlarged view of theportion A in FIG. 2, where FIG. 2A is also a comparative figure withrespect to FIG. 3, for FIG. 2A shows the surface of the metallicsubstrate without the moderation of the etch-moderating agent. FIG. 3shows an uneven structure 104 formed on the surface layer 103 afteretching through the companion of the etch-moderating agent. It is worthnoting that these figures only reveal perspective views of the instantdisclosure, where the surface of the metallic substrate will havesubstantially arched, irregular, uneven structure formed thereon to havespecial textures after the etching process.

For the instant embodiment, the etchant is a solution containing atleast one type of transitional metal salt. To provide furtherexplanations, the etchant can be a solution containing at least one typeof transitional metal salt selected from the group consisting of iron,copper, nickel metal salt and a mixture thereof, such as the ironchloride, copper sulfate, nickel sulfate, where the concentrationthereof can range from 0.1 to 10 g/L. The etch-moderating agent can be along-chain surface-active agent, where the etch-moderating agent can bea solution selected from the group consisting of cations, anions,non-ion long-chain surface-active agents and a mixture thereof, wherethe concentration of the etch-moderating agent can range from 1 to 500PPM (part per million).

For the etching process of the instant embodiment, a preferred parameterincludes an etchant having 3.2 g/L of iron chloride (FeCl₃) and 0.6 g/Lof copper sulfate (CuSO₄). Furthermore, the etch-moderating agentincludes sodium dodecylbenzenesulfonate of 50 PPM, where the temperatureis 40±5 degrees. Furthermore, the time spent for the etching processlasts for 1-15 minutes and can be adjusted to practical needs. For theetching process of the aluminum alloy substrate using the copper sulfatesolution, the chemical expression is stated as followed:3Cu⁺²+2Al→3Cu+2Al⁺³.

After the etching process, the second pretreatment P2 using the chemicalpolishing process is performed on the metallic substrate. In otherwords, a foggy surface is produced on the metallic substrate through thechemical polishing process. To provide further illustrations, thepretreatment P2 includes a step P21 of first pickling on the metallicsubstrate, a step P22 of chemical polishing on the metallic substrate,and a step P23 of second pickling on the metallic substrate. After eachof the aforementioned steps, the metallic substrate is rinsed with waterfor at least once, where the water rinsing step may range from one tofive times. Preferably, two times of water rinsing is implemented.

The pickling process utilizes an acidic solution having a concentrationwhich ranges from 1 to 50 ml/L to perform under a temperature thatranges from 10 to 90 degrees. A preferred parameter for the picklingprocess of the instant disclosure utilizes a nitric acid solution havinga concentration of 20 ml/L under a temperature approximately 25 degrees.

The chemical polishing utilizes one or many acidic solutions having aconcentration that ranges from 1 to 85 degrees, such as the phosphoricacid or the sulfuric acid and etc., under a temperature that ranges from10 to 90 degrees. A preferred parameter for the chemical polishingprocess of the instant disclosure utilizes a phosphoric acid solutionhaving a concentration of 85% under a temperature that ranges from 90 to93 degrees for 1 to 10 seconds. It is worth noting that the gloss forthe chemical polishing process is suggested to keep less than 6 in orderto form the skid-proof leather-texture surface disclosed in the instantdisclosure.

Next, the anodic treatment step S3 forms an oxidized film havingmicro-porous structure on the surface of the metallic substrate. Apreferred parameter for the anodic treatment of the instant disclosureis provided in the following table 1.

TABLE 1 parameters regarding the anodic treatment (step S3) of theinstant disclosure. Sub- Parameter procedures Parameter 1 Parameter 2Anodic Sulfuric acid and/or oxalic Temperature: 5-50° C. treatment acidor phosphoric acid Current density: 0.2-3.0 A/dm² and/or boric acidand/or Time spent: 10-60 min tartaric acid 1-95% Water Temperature:5-95° C. 1-5 times rinsing

Through experimental results, a preferred parameter for the anodictreatment includes dipping the substrate into a sulfuric acid solutionhaving a concentration that ranges from 20 wt % to 25 wt % under atemperature that ranges from 15 to 25 degrees. Furthermore, the currentdensity is 1.4 A/dm² and the time spent last for at least 30 minutes. Toprovide further explanations, the water rinsing process is implementedtwice under a temperature of approximately 25 degrees.

A step S4 to activate and increase the dyeing effect of the surface ofthe metallic substrate is performed after the anodic treatment.Specifically speaking, an activating agent is utilized to enhance theactivity of the substrate surface for the latter processes. A parameterfor the activating process utilizes an acidic solution having aconcentration of 1 to 50 ml/L for 0.1 to 5 minutes under a temperaturethat ranges from 5 to 95 degrees. Next, 1 to 5 times of water rinsing isimplemented. For a preferred parameter of the instant disclosure, anitric acid solution having a concentration of 20 ml/L is utilized undera temperature approximately 25 degrees before performing two times ofwater rinsing under the same temperature 25 degrees. The activatingprocess provides the effect of removing the silicone impurities producedby the anodic oxidation to increase the dyeing effect of the metallicsubstrate.

A step S5 of dyeing the surface of the metallic substrate is performedafter the activating process. This dyeing step utilizes acommercial-grade aluminum alloy dye to dye under a temperature thatranges from 5 to 50 degrees for 0.1 to 10 minutes. A preferred parametersuggests a temperature of 40 degrees and a time spent that ranges from 1to 6 minutes. To provide further explanations, the water rinsing processis implemented also twice under a temperature of approximately 25degrees.

In order to improve the dirt-proof effect of the oxidized film, a stepS6 of sealing is performed to seal the micro-porous structure on thesubstrate surface by using a sealing agent. Generally, acommercial-grade nickel acetate sealing agent is utilized for sealingafter the anodic treatment. The instant disclosure utilizes acommercial-grade nickel acetate sealing agent having a concentration of1 to 15 g/L under a temperature that ranges from 5 to 95 degrees for 5to 90 minutes. It is worth noting that the aforementionedcommercial-grade nickel acetate sealing agent refers to current sealingagents which consist mainly of nickel acetate salts.

A preferred parameter for the sealing process dips the aluminum alloysubstrate in a commercial-grade nickel acetate sealing agent having aconcentration of 7 g/L under a temperature of 90±5 degrees for 30minutes.

Finally, a step S7 of ash-removing to clean the surface of the aluminumalloy substrate is implemented to remove the ash-like substances adheredon the substrate. Generally, the ash-removing process utilizes adedusting agent which consist mainly of acidic solutions to clean thesubstrate before water rinsing the substrate. A parameter for theash-removing process utilizes an acidic solution having a concentrationof 1 to 50 ml/L under a temperature that ranges from 5 to 95 degrees.Next, the water rinsing process is implemented 1 to 5 times under atemperature that ranges from 5 to 95 degrees.

In order for the instant disclosure to be adaptable to housings ofelectronic devices, preferably, the ash-removing process utilizes anitric acid having a concentration of 20 ml/L under a temperatureapproximately 25 degrees. Next, the water rinsing process is performedtwice under a temperature approximately 25 degrees.

With reference to FIG. 4, after the method of forming a skid-proofleather-texture surface on the metallic substrate, a skid-proofleather-texture surface is formed on the aluminum alloy substrate. Afterperforming the etching process on the metallic substrate surface, anuneven structure 104 is formed thereon. Next, after the processes ofchemical polishing, pickling, the anodic treatment and latter processesetc., the uneven structure 104 shown in FIG. 3 is formed into a moredelicate particle structure 105. The particle structure 105, afterundergoing the etching process and the anodic treatment, will have aleather-texture surface formed thereon. Hence, providing the users witha skid-proof leather-texture sensation when touched.

The texture of the surface, after the etching process of the instantdisclosure, will be much similar to a leather-texture surface which isuneven and irregular. Next, the uneven structure will be formed into amore delicate particle structure after the anodic treatment. It is worthnoting that such surface is very much different from the surface formedthrough simply sand-blasting as the surface formed through sand-blastingis rough and ragged with irregular-shaped holes thereon. However, thesurface formed through the etching process and the anodic treatment ofthe instant disclosure is very delicate.

Generally, the electronic devices after having the metallic housingsurfaces thereof being processed, the surfaces may be too smooth or evenslippery for the users upon holding. Thus, through the method providedin the instant disclosure, a delicate particle structure can be formedon the metallic surface. Accompanied with the etching process of theinstant disclosure, a skid-proof leather-texture surface can be formedon the substrate. Therefore, the surface of the metallic substrate ofthe instant disclosure can provide the users with a leather-texturesensation when touched, meanwhile having a skid-proof effect.

The descriptions illustrated supra set forth simply the preferredembodiments of the instant disclosure; however, the characteristics ofthe instant disclosure are by no means restricted thereto. All changes,alternations, or modifications conveniently considered by those skilledin the art are deemed to be encompassed within the scope of the instantdisclosure delineated by the following claims

What is claimed is:
 1. A method of forming a skid-proof leather-texturesurface on a metallic substrate, comprising the following steps of:providing a metallic substrate, performing a first pretreatment to cleanthe surface of the metallic substrate; etching the surface of themetallic substrate through an etchant while using an etch-moderatingagent to moderate the condition of etching; performing a secondpretreatment on the surface of the metallic substrate; performing ananodic treatment on the surface of the metallic substrate to form anoxidized film having micro-porous structure thereon; activating thesurface of the metallic substrate after the anodic treatment; dyeing thesurface of the metallic substrate; sealing the micro-porous structureformed on the surface of the metallic substrate; and ash-removing toclean the metallic substrate.
 2. The method of forming a skid-proofleather-texture surface on a metallic substrate according to claim 1,wherein the step of performing the first pretreatment on the metallicsubstrate includes a sub-procedure of degreasing and water rinsing onthe surface of the metallic substrate.
 3. The method of forming askid-proof leather-texture surface on a metallic substrate according toclaim 1, wherein the etchant consist of at least one solution containingtransitional metal salt, and wherein the etch-moderating agent is along-chain surface-active agent.
 4. The method of forming a skid-proofleather-texture surface on a metallic substrate according to claim 3,wherein the etchant contains at least one metallic salt solutionselected from the group consisting of metal, copper and nickel salt; andwherein the etch-moderating agent contains at least one long-chainsurface-active agent selected from the group consisting of anion,cation, and non-ionic long-chain surface-active agents.
 5. The method offorming a skid-proof leather-texture surface on a metallic substrateaccording to claim 3, wherein the metallic substrate is an aluminumalloy substrate, and wherein the etchant consists of 3.2 g/L of ferricchloride and 0.6 g/L of copper sulphate under a temperature of 40±5degrees, wherein the etch-moderating agent includes sodiumdodecylbenzenesulfonate of 50 PPM.
 6. The method of forming a skid-proofleather-texture surface on a metallic substrate according to claim 1,wherein the process of performing the second pretreatment on the surfaceof the metallic substrate includes a pickling and a chemical polishingprocess to produce a foggy surface on the metallic substrate.
 7. Themethod of forming a skid-proof leather-texture surface on a metallicsubstrate according to claim 6, wherein the pickling process uses anitric acid solution of 5 ml/L under a temperature of 25 degrees.
 8. Themethod of forming a skid-proof leather-texture surface on a metallicsubstrate according to claim 6, wherein the chemical polishing processuses a phosphoric acid of 85% at a temperature which ranges from 90 to93 degrees for 1 to 10 seconds.
 9. The method of forming a skid-proofleather-texture surface on a metallic substrate according to claim 8,wherein the gloss of the chemical polishing process is smaller than 6.10. The method of forming a skid-proof leather-texture surface on ametallic substrate according to claim 1, wherein the anodic treatmentincludes dipping the substrate into a sulfuric acid having aconcentration that ranges from 20 wt % to 25 wt %, where the temperatureranges from 15 to 25 degrees, the current density is 1.4 A/m², and theprocessing time last for at least 30 minutes.
 11. The method of forminga skid-proof leather-texture surface on a metallic substrate accordingto claim 1, wherein the activation of the metallic substrate includesdipping the substrate into a nitric acid of 20 ml/L at a temperature of25±5 degrees.
 12. The method of forming a skid-proof leather-texturesurface on a metallic substrate according to claim 1, wherein the dyeingstep utilizes a aluminum alloy dye to dye the metallic substrate under atemperature that ranges from 5 to 50 degrees for 0.1 to 10 minutes. 13.The method of forming a skid-proof leather-texture surface on a metallicsubstrate according to claim 1, wherein the sealing step includesdipping the aluminum alloy substrate into a nickel acetate sealing agenthaving a concentration of 7 g/L under a temperature that ranges from90±5 degrees for 30 minutes.
 14. The method of forming a skid-proofleather-texture surface on a metallic substrate according to claim 1,wherein the ash-removing step includes the utilizing a nitric acid of 20ml/L under a temperature that ranges from 20±5 degrees.